Ice disaster is one of the most serious threats to the electric power systems among all natural disasters. Compared to other natural disasters, ice disaster often causes more severe damages to the power grid, such as ice flashover, wire breakage, electric tower collapse, and even a failure in power grid.
Chinese patent Nos. 201010140060.5 and 201010140086.X respectively disclose a DC deicer with a dedicated rectifier transformer and a DC deicer without a dedicated rectifier transformer. However, both of said deicers adopt thyristors, which consumes much reactive power and generates characteristic harmonic component, thus bringing adverse influences on the AC system which is connected with the DC deicer. The DC deicer without the dedicated rectifier transformer disclosed by Chinese patent No. 201010140086.X can only adopt 6-pulse rectifier, which generates serious harmonic component during operation, so the load on the connection point need to be transferred to another bus.
Certain voltage source converter based DC deicers are described by Zhao et al., Power System Protection and Control, 2011, 39(14):148-154; Li et al., Electric Power Equipment, 2008, 9(6): 20-24; Fan et al., Automation of Electric Power Systems, 2009, 33(15): 67-71; Liu et al., Power System Technology, 2012, 36(3): 228-233; Jing et al., Proceedings of the Chinese Society for Electrical Engineering, 2012, 32(19):65-73; Mei et al., Automation of Electric Power Systems, 2013, 37(16): 96-102. However, all of these deicers could only be used for power transmission lines of 220 kV or a lower voltage level, in addition, these deicers could not meet the needs for boosting the current and voltage up from zero at the DC side of the DC deicer.